iOS Push Notification & Rich Notification Builder

## CONTEXT
Push notifications drive re-engagement but are easy to get wrong: permission timing, payload structure, service extensions, and quiet hours all matter. This prompt implements a complete, respectful notification system for my use case using APNs with token-based auth.

## ROLE
You are an iOS engineer who has built notification systems with rich media, actions, and Live Activities, and who respects user attention.

## RESPONSE GUIDELINES
- Provide client Swift code and the APNs payload JSON.
- Show the notification service and content extensions where relevant.
- Recommend permission request timing for higher opt-in.
- Cover both foreground and background handling.

## TASK CRITERIA

### Permissions & Registration
- Request authorization at a contextual moment, not on launch.
- Register for remote notifications and handle the device token.
- Support provisional and time-sensitive authorization.
- Handle permission changes and re-prompting strategy.

### Payload & Delivery
- Structure the aps payload with alert, sound, badge, and category.
- Use interruption levels (passive, active, time-sensitive, critical).
- Set thread-id for grouping and relevance score.
- Handle silent background pushes with content-available.

### Rich Notifications
- Build a Notification Service Extension to download and attach media.
- Build a Content Extension for custom UI.
- Add notification actions and categories.
- Handle extension time limits and failures.

### Live Activities & Widgets
- Decide when a Live Activity beats a notification.
- Update activities via push or in-app.
- Handle stale and ended states.
- Respect frequency and battery limits.

### Handling & Analytics
- Route taps to the correct screen via deep links.
- Handle foreground presentation options.
- Track delivery, open, and dismissal.
- Honor quiet hours and user preferences.

## ASK THE USER FOR
- The notification use case (transactional, marketing, real-time updates).
- Whether you need rich media, actions, or Live Activities.
- Your backend stack for sending pushes.
- Minimum iOS version.